The United Nations' special envoy for Afghanistan, Lakhdar Brahimi, is reportedly trying to negotiate among rival groups in order to get the assembly back on track.

Yesterday, about 40 percent of the delegates participating in the constitutional assembly boycotted a vote due to proposed changes in the draft constitution. The main differences at the Loya Jirga have erupted over the scope of presidential powers. The chairman of Afghanistan's Transitional Administration, Hamid Karzai, has repeatedly said he will not stand in future presidential elections if a strong presidential system is not approved.

Observers say the split at the assembly is mainly between two groups -- the Pashtun supporters of Karzai's current pro-Western government and the Tajiks, Uzbeks, and other smaller ethnic groups.

Leaders of protesting delegations include former President Burhanuddin Rabbani, Uzbek leader Abdul Rashid Dostum, and Islamic conservative Abdul Rab al-Rasul Sayyaf. They are seeking more representation in the government through a stronger role for the country's parliament and provincial legislatures.

Yesterday, the European Union's envoy to Afghanistan, Francis Vendrell, expressed concern over what he called an "ethnic polarization" at the Loya Jirga that he said could be "very damaging."

The bulk of the constitution has been agreed on but differences are said to remain on several key articles, including the country's official languages and dual nationality. Many delegates from the Tajik, Uzbek, and Hazara ethnic groups refused to vote yesterday for fear that their rights were being disregarded.

A female delegate told RFE/RL's Afghan Service that representatives of 18 provinces boycotted the voting yesterday. "The rights of other ethnic groups are not being respected. We want all the delegates to obtain their rights. Because of that, we decided not to vote," she said.

Mohammed Raouf Mahdi, a delegate representing Afghan refugees living in Iran, said one group of delegates had refused to vote because the head of the Loya Jirga, Sebghatullah Mujadadi, called them "infidels" after they suggested that Afghanistan should be called the Republic of Afghanistan instead of the Islamic Republic of Afghanistan.

"It is against human rights and the right of delegates to freely vote. Delegates want to express themselves freely, but [Mujadadi] took that right away from them," Mahdi said.

Some of the 502 delegates in attendance have criticized the Loya Jirga for lacking transparency, while others said their viewpoints had not been reflected in the new text presented by the Reconciliation Committee. The committee was supposed to unite the views of all the delegates, who had been broken into 10 groups to discuss the draft.

According to the presidential decree on the Loya Jirga, final approval of the draft constitution will be by simple majority. However, analysts warn that a constitution that does not have widespread support could paralyze the country.

Since mid-December, delegates representing all regions of Afghanistan, as well as the country's ethnic and minority groups, have been debating a draft constitution unveiled by Karzai's government. The ratification of the new constitution -- the country's seventh written constitution -- would pave the way for Afghanistan's first democratic elections, tentatively scheduled for June.